JPH05117710A - Abnormality detector of electrical sintering device - Google Patents

Abstract

PURPOSE:To immediately detect the abnormality of a sintering die in sintering and to prevent the breakage, scattering, etc., of the die or sintered body by vertically providing a strip conductor on the outer surface of the die made of an insulator and used to sinter a conductive raw powder and connecting the upper and lower ends to a current detector. CONSTITUTION:A conductive raw powder 22 is filled in a sintering die 20 made of an insulating material and pressed by the upper and lower punches 23 and 24, and a voltage is impressed on the punches 23 and 24 from a power source control part 25 to pass a heavy current through the raw powder 22 which is heated by the Joule heat and sintered. A strip conductor 27 is vertically fixed to the outer surface of the die 20. When the die is broken in sintering, for example, the conductor 27 is cut, the current is reduced to zero, the fact is detected by a detector 28 connected to both ends of the conductor 27, hence a stopping means 29 is actuated, the pressing of the punches by a pressing force control part 26 and the sintering current supply by the control part 25 are instantly stopped, and the breakage and scattering of the sintered body by the die 20 and raw powder 22 are prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for applying a voltage to a powder raw material through an electrode in a state where a conductive powder raw material such as metal, carbide or nitride filled in a sintering type sintering space is pressurized. The present invention relates to an abnormality detection device for an electric current sintering device that applies and heats and sinters.

[0002]

2. Description of the Related Art Conventionally, an electric current sintering apparatus for electrically conductively sintering a conductive powder material uses a so-called EDC method (see Japanese Patent Laid-Open No. 2-125802) and a so-called PAS method. ("Nikkei Mechanical" Nikkei McGraw-Hill Co., Ltd.
Issued July 9, 1990, see pages 88-89).

A current-flowing sintering apparatus utilizing the EDC method is shown in FIG.
As shown in Fig. 2, a pair of electrodes 2, a spacer 3, and bottom wall plates 4 and 5 are interposed between a pair of side wall plates 1 and these are integrally fastened with a fastener 6 to form a sintering die 7. A punch 10 for pressing the powder raw material 9 filled in the sintering space 8 of the sintering die 7 is provided on the upper side. When sintering the powder material 9, the powder material 9 is pressed by the punch 10 and a large current is applied to the powder material 9 through the pair of electrodes 2 for a very short time of 10 to 500 μsec. The powder is melted and vaporized only in the superficial layer portion or the contact portion of the powder, and diffusion is promoted and sintering is performed while maintaining the rapid cooling characteristics of other portions.

The electric current sintering apparatus using the PAS method is shown in FIG.
As shown in Fig. 1, a sintering type of integral structure having a sintering space 11
A punch 13 and electrodes 14 are provided above and below 12,
At the time of electric current sintering, the powder material 15 is pressed to the upper and lower punches 13 with a smaller pressing force to increase the contact resistance between the powders, and the powder material 15 from the pair of electrodes 14 through the punch 13 has a small current and a large electric power. Is supplied to increase the internal energy of the powder due to the discharge pressure, thereby promoting diffusion and sintering.

[0005]

However, in any conventional electric current sintering apparatus, no measures have been taken to detect cracks or the like in the sintering molds 7 and 12. For this reason, in the former case, a high voltage of 3 KV or more and a large current of 50 KA / cm ² or more are instantaneously applied under pressure, so if there is damage such as cracks in the sintering die 7, a shock wave or short circuit will occur. Due to this, the sintering mold 7 and the sintered body were destroyed and scattered, which was extremely dangerous. Also, even if the mold cracked during pressing or energization, energization could not be stopped.

This point also applies to the latter case. In view of the above conventional problems, it is an object of the present invention to make it possible to immediately detect the occurrence of mold cracks or the like in the sintering mold.

[0007]

According to the present invention, a conductive powder raw material 22 filled in a sintering die 20 is pressed to obtain the powder raw material 22.
In a current-carrying sintering apparatus that applies a voltage to 22 to heat and sinter, a conductor 27 is attached to the surface of the sintering die 20.
The detector 28 for detecting the disconnection is provided.

[0008]

[Function] When a mold crack or the like of the sintering die 20 occurs during pressurization or energization, the conductor 27 mounted on the surface of the sintering die 20 is cut, and the detector 28 detects the cutting. Therefore, a mold break or the like can be immediately detected. When the detector 28 detects the disconnection, the stopping means 29 operates to stop the pressurization and energization. Therefore, it is possible to prevent the sintering die 20 and the sintered body from being broken or scattered, and it is possible to take measures such as replacing the sintering die 20.

[0009]

Embodiments of the present invention will now be described in detail with reference to the drawings. 1 and 2 illustrate a first embodiment of the present invention.
In FIG. 1, 20 is a sintering type made of an insulating material, and a sintering space 21 inside thereof is filled with a conductive powder material 22. The powder raw material 22 is pressed by upper and lower punches 23 and 24, which are fitted on the upper and lower sides of the sintering die 20 and also serve as electrodes, and a voltage is applied through the upper and lower punches 23 and 24.

Reference numeral 25 is a power supply control unit for controlling the voltage applied to the powder raw material 22 through the upper and lower punches 23 and 24. Reference numeral 26 is a pressing force control unit for controlling the pressing force A applied to the upper punch 23 by a pressurizing cylinder (not shown). Reference numeral 27 denotes a belt-shaped conductor, which is mounted on the surface of the sintering die 20 over the entire length in the vertical direction at predetermined intervals in the circumferential direction, as shown in FIG. The conductor 27 is designed to be easily cut when a crack or the like occurs in the sintering die 20.

28 is a detector for detecting the breakage of the conductor 27,
It is connected to both ends of each conductor 27, respectively. Since the electric resistance of the detector 28 becomes infinite when the conductor 27 is cut, a resistance meter is used so as to detect the break of the conductor 27 by the change in the resistance value. 29 is a stop means, when the detector 28 detects the disconnection of the conductor 27,
The power supply controller 25 and the pressure controller 26 are operated to stop energization and pressurization.

In the above structure, the resistance value of the conductor 27 is monitored by the detector 28 during operation. If a mold crack or the like occurs in the sintering die 20 during pressurization or energization, one of the conductors 27 among the plurality of conductors 27 mounted on the surface of the sintering die 20.
Is cut, and the resistance value of the conductor 27 rapidly becomes infinite as shown in FIG. Then, the detector 28 detects the disconnection of the conductor 27 due to the change of the resistance value, and the stop means 29 operates to operate the pressurizing force control unit 26 and the power supply control unit 25, respectively, and stop the pressurization and energization.

Therefore, when damage such as mold cracking occurs in the sintering die 20, the detector 28 can immediately detect it. Also, by stopping the pressurization and energization, damage and scattering of the sintering die 20 and the sintered body can be prevented in advance, which improves the safety during operation and facilitates the replacement of the sintering die 20. , Loss time due to post-treatment of fragments, etc. can be reduced and productivity is improved.

A mold handling device is provided for the detector.
If the die handling device is operated by detecting the die cracking in 28, unattended operation is possible by automatically exchanging the sintering die 20. FIG. 4 shows a second embodiment of the present invention, in which a relay 30 is used as the detector 28 instead of the resistance meter. That is, the relay 30 is connected to both ends of each conductor 27 together with the power supply 31. The output contact 32 of the relay 30 is connected to the stopping means 29.When the conductor 27 is cut off, the relay 30 is demagnetized and the output contact 32 is turned on to input a signal to the stopping means 29. ing.

FIG. 5 shows a third embodiment of the present invention, which is a conductor.
27 illustrates a modified example of the mounting structure of 27. FIG. 5A shows a structure in which vertical conductors 27 are mounted on the surface of the sintering die 20, and the conductors 27 are connected in a zigzag manner at the upper and lower connecting portions 33 to form a single unit as a whole. is there. FIG. 5B
Is a structure in which the conductors 27 are mounted in the circumferential direction, and the conductors 27 are connected to each other at the connecting portions 33 in a zigzag shape.

In FIG. 5C, one conductor 27 is spirally mounted. As described above, there are various methods of mounting the conductor 27, and any of them may be adopted or combined.

[0017]

According to the present invention, the detector 28 for mounting the conductor 27 on the surface of the sintering die 20 and detecting the disconnection of the conductor 27 is provided.
Since the above is provided, it is possible to immediately detect a mold crack or the like of the sintering die 20.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a perspective view of a sintering die showing the first embodiment of the present invention.

FIG. 3 is a resistance characteristic diagram showing the first embodiment of the present invention.

FIG. 4 is an overall configuration diagram showing a second embodiment of the present invention.

FIG. 5 is a perspective view of a sintering die showing a third embodiment of the present invention.

FIG. 6 is a perspective view showing a conventional example.

FIG. 7 is a perspective view showing a conventional example.

[Explanation of symbols]

 20 Sintering type 22 Powder raw material 23 Upper punch 24 Lower punch 25 Power control unit 26 Pressure control unit 27 Conductor 28 Detector 29 Stopping means

Claims (1)

[Claims] 1. An electric current sintering apparatus for pressurizing a conductive powder raw material (22) filled in a sintering die (20) and applying a voltage to the powder raw material (22) to heat and sinter the powder. An abnormality detection of an electric sintering machine characterized in that a conductor (27) is mounted on the surface of the sintering die (20) and a detector (28) for detecting disconnection of the conductor (27) is provided. apparatus.